Improving the Holocene glacier chronology of the Southern Alps/New Zealand enabling its reliable utilisation as palaeoclimatic archive

• Applicant: Professor Dr. Stefan Winkler
• Subject Area: Physical Geography
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439448631

Mountain glaciers are impressive indicators of present climate change and concurrently constitute high-resolution palaeoclimatic archives. Investigating Holocene glacier fluctuations provides valuable insights into their dominating climatic drivers, indispensable knowledge for any subsequent assessment of modern or prediction of future changes. Reliable interpretation of Holocene glacier archives and their correlation on global scale are essential for the understanding of global climate dynamics with their hemispheric and global interconnections. Apart from satisfactory spatial diversity this requires credible and representative regional data sets. Recent global compilations of Holocene glacier chronologies reveal, however, that only for very few mountain regions these requirements are fulfilled. Existing uncertainties prevent a sustainable utilisation of mountain glacier’s potential as palaeoclimatic archives. This constitutes a highly unsatisfactory situation.The Southern Alps of New Zealand’ are considered one of the rare key localities in the Southern Hemisphere for investigating Holocene glacier chronologies. Verified utilisation of their Holocene glacier chronology as palaeoclimatic archive fails, however, due to shortcomings in robustness and representativeness of work published to date. This has meanwhile been recognised beyond all doubt. Detailed reassessment revealed that several previously established glacier advances need to be dismissed, mainly due to major geomorphological uncertainties caused by strong regional morphodynamics. As a result, the Holocene glacier chronology of New Zealand should currently not be considered with palaeoclimatic interpretations on hemispheric or global scales. The existing uncertainties bear a substantial risk of subjective interference/bias and unjustified adjustment to preferred paradigms. Main aim of the proposed project is to establish a reliable Holocene glacier chronology applying Schmidt-hammer exposure-age dating (SHD) in combination with terrestrial cosmogenic nuclide dating (TCND). The selected approach particularly allows, in particular, to address and to tackle the specific regional uncertainties in line with an expansion of spatial diversity, major weakness of previous work. And unlike to chosen approach, terrestrial cosmogenic nuclide dating alone could not overcome these shortcomings. Intended outcome is a reliable and regionally representative Holocene glacier chronology for the Southern Alps, a result measuring up their potential as valuable climate archive. It should enable a palaeoclimatic analysis in combination with correlations to other glacier regions on regional, hemispheric, and global scales independent and unbiased by any predetermined paradigms.

• DFG Programme: Research Grants